SequenceGarage

I've got a wilwood proportioning valve in today, thought i'd post this in motorsports since you guys are likely the only ones to understand the need.

Setup:

Stock master
ABS removed
Z32 30mm fronts with brembo blanks and Hawk HP+
Stock rears with Porterfield R4
Motul dot 5.1

going to full race pads in the front soon.

235F and 265R with just a GP sports aero kit but no wing or splitter or anything.

So this is my question. Wilwood does not reccomend putting the vavle on the front line, I assume because it requires more peddle pressure, and possibly because the posibility of giving youself a rediculously dangerous bias puts wilwood in an awkward position, however I have way too much front bias, will using this valve on the front be really that bad? And if so what can I do to give myself way too much rear bias, and then use the wilwood valve on the rears?

Unless a huge problem is presented, like I'm going to be boiling fluid or not being able to slow the car down because the peddle pressure is so heavy (neither which I can see happening) I think I'm going to do it

Thanks take care.

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Sasha Anis
Sequence-Garage

jmauld

I would imagine that they are concerned about the part failing and losing all of your front brakes.

I haven't dug into the braking system on this car too much yet, but do our cars have a proportioning valve seperate of the master cylinder or is it built in to the M/C?

If it's seperate, then you will probably need to bypass that completely. That will allow for more bias to the rear, which you can then reduce to the level you need with the Wilwood part.

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Jason
'95 240sx SE

R33GTS-T

you're going to be using a proportioning valve on a street car ........i would NEVER do that.....its just asking to crash your car and seriously endanger yourself, your passangers, and the other people on the road/side walks......in all honesty......work on your pad setups to compensate for brake biased if this is a street/track car........if this is a track ONLY car and it never sees street duty then a proportioning valve is awesome

also if you're going to run track pads on the street be prepared to very frequently be changing your pads and rotors......when you run higher coefficients of friction on the street the pads never get up to their optimal operating temperature.......thus braking performance decreases AND they will be shot in no time.......trust me i ran a set of CarboTech PantherPlus pads (coefficient of friction of .54) and they were awesome for the track but they were shot.....along with my rotors in 9 months.......i drove the car as a daily driver.......if you're going to be buying a pad that is any more aggressive than that one i would not drive the car on the street as you'll be too prone to locking up the tires (the pads are designed for race compound only) and you'll need to replace pads and rotors too frequently which will get expensive

sorry for the long post.......i just don't want to see you do anything that would put you at risk

Late,
Daniel

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does your wife drive a wide-bodied sr-powered coupe???

jmauld

That's another reason why you should only run the prop valve on the rear. The systems "should" be seperate from the M/C down, so if you lose your rear brakes, you still have the fronts.

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Jason
'95 240sx SE

SequenceGarage

thanks for the concern, the car is only a track car and no longer sees street duty.

As for loosing your breaks, if you have a major leak anywhere in the system it wont take long before hte master cylinder is totally out of fluid, and then neither the fronts nor rears will be producing any pressure. This isn't a huge concern for me because if i started to loose my brakes I would notice quite quickly (loosing pedal pressure is almost instantaneous) and then just crawl the car back into the pits.

As for brake bias on the street, how does chaning pad selection to alter brake bias differe from using a proportioning valve?

In my opinion you should use the same pads all around so that the car has a consistant feeling. For example, the way i have the car setup now it will start off with tons of front bias, and as the brakes get hot the bias will continously go further and further back. Definatly NOT a good idea (and why i need porterfields for the front). If I have a proportioning valve the bias will stay constant across the entire temperature range.

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Sasha Anis
Sequence-Garage

jmauld

On a track car, you should find out how hot your brakes are getting and use pads that work effectively in those temp ranges. It may not end up being the same pad.

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Jason
'95 240sx SE

R33GTS-T

by using brakes pads to differ brake bias as opposed to a proportioning valve....there isn't an increased chance of loosing brake fluid b/c of a problem with the brake pads

i too agree though in the theory of using the same pads front and rear....however i know that some drivers prefer to use upgraded pads in the front and stock pads in the rear

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does your wife drive a wide-bodied sr-powered coupe???

Ian

yeah, i also have alot of front bias...but i also have the issue of the rears locking up first (i think...it's hard to say)


i heard that this is because of the Z32 fronts being so much larger, that the stock proportioning allows for too little fluid to the front brakes to clamp. Basically saying that since the fronts are larger, it takes more fluid to clamp them down effectively, and by this time the rears are already full up...does this make sense?

how can i fix this?

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Team Pterodactyl
SHARK ATTACK!!!
LookOutDrift

SequenceGarage

Put the bias valve in today and removed ABS, here are some pics.

The setup goes like this:

Front Master > 10x1.00 Female-Female adapter > Bias Vavle > 10x1.00 3 way adapter (from rear passenger side distrobution block from nissan) > 2 front brakes

Rear master > 10x1.00 Female-Female adapter > back to the stock 3 way tee and the rear brakes.



the lines I made have a 10x1.00 fitting on one end, and the fittings that came with the wilwood vavle on teh other end. It was the only way to make it work without going custom stainless lines.

As for driving impressions, I have a track day coming up on the 14th of may I'll let you guys know how much better or worse she is. I can't see it possibly being worse.

On a side note I took my stock spolier off it makes the ass look so perky I love it

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Sasha Anis
Sequence-Garage

R33GTS-T

nice clean install

definitely let us know how it works out at the next track event

on a side not how come this forum only sends me emails SOMETIMES but other times NEVER sends me email notifications

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does your wife drive a wide-bodied sr-powered coupe???

aaronyoung

from the stoptech site...
"We could start this section by clearly stating that you should not modify your proportioning valve. But, what fun would that be? In all seriousness, making changes to the proportioning valve to effect brake bias should be left to those with the proper tools and measurement devices, but if you have tweaked your vehicle beyond recognition, this may be your only solution to restore a sense of proper bias to your braking system.

We’ll start here with three of the most basic rules regarding proportioning valve installation and selection.

1. If you have the deeply-rooted need to install your own adjustable proportioning valve, be advised that they should NEVER be installed if the factory unit is still in place. Proportioning valves in series with one another can do nasty, unpredictable things!

2. If you have the deeply-rooted need to install your own adjustable proportioning valve, be advised that they should NEVER be installed in-line to the front brakes. The effect would be to make your vehicle rear-biased before you could say “terminal oversteer.” Front brake line pressure should always be left alone – only the rear pressures should be considered for proportioning.

3. In all cases, the basic brake system balance needs to be close to optimized to start with. This is the only way that a proportioning valve can be effectively utilized. You should never assume that simply adding a proportioning valve will address all rear-bias conditions, as even the best proportioning valves must be well-matched to the target vehicle."

for the full article go to ...
http://www.stoptech.com/whitepapers/...ing_valves.htm

lots of good info on that site.

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"there's someone in my head but it's not me"

R33GTS-T

excellent post.....thanx for the info

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does your wife drive a wide-bodied sr-powered coupe???

originalsin

flush ur brake system and run dot 5 fluid, it has a much higher boiling point but u CANT mix it with dot 3 or dot 4

R33GTS-T

you don't mean TRUE dot 5 fluid.....as that is meant for construction vehicles and things of that nature that truely do not move around frequently or at very high speeds......dot 5 brake fluid is NOT recommended for cars.......what race cars use is not TRUE dot 5 brake fluid.....just something that is comparable to dot 5 but has the ability to withstand being thrown all over the place

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does your wife drive a wide-bodied sr-powered coupe???

aaronyoung

yup stay away from dot 5, dot 5.1 however is great.
more stuff from the stoptech site regarding brake fluid...
http://www.stoptech.com/whitepapers/brakefluid1a.htm

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"there's someone in my head but it's not me"

SequenceGarage

Sounds like i'm gonna be in for a lot of fun, I did everything you're NOT supposed to do!



i'm going totrack on saturday i'll slowly adjust it from nothing to something and let you guys know how it works, im sure as long as im not a jackass about it i'll be fine. I only want to pull like 5% front line pressure.

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Sasha Anis
Sequence-Garage

SequenceGarage

So I went to the track on saturday and had no problems with the brakes what so ever, then again I was drifting so the brakes didn't heat up too much. I did do some racing later on in the day - however it was raining so it killed the fun. But i didnt have CRAZY REAR BIAS OMG BBQ to the point that I went into a wall, you guys should all do this Its the best 100$ I've ever spent. I should have added more bias to the rear in the wet. Man the fronts lock up like nothing in the wet.

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Sasha Anis
Sequence-Garage

thx247

adding the bias to the fronts reduces braking force up front. No reason to do that because the fronts do most of the braking. Add it to the rear and decrease line pressue until the rears lock up just after the fronts.

Changing pad compounds front and rear lets you adjust bias without a valve, street pads in the rear will overheat pretty quickly on the track.

Do you have a way to measure stopping distance or braking force? Thats the only way you'll know if you changes made a positive improvement.

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Finally down to 1 car again. Thank god.

SequenceGarage

1) A brake bias valve such as mine reduces line pressure. Put it on the front = reduce front line pressure

2) Only one type of pad will suit a certain setup. Using alternitive pads that lower your efficiency will only create more heat in your braking setup, and the bias will change depending on how hard you're braking and how hot hte brakes are. Not exactly my favorite way of doing things, too many variables.

3) See which wheels lock first, tune until the rear locks first, then keep backing it off until the fronts lock first just hardly. Also straight line braking is not always the most important aspect, you might want a bit more front bias so you can trail brake a bit harder without sliding the bitch. In that respect its also driver preferance. I like to drive into corners under brakes myself.

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Sasha Anis
Sequence-Garage

RBS14

this relates to brake bias, but not porportioning valves. I found out that Z31 Non-Turbo MC's are 15/16 and have the same split point as S14k's (which have z32 30mm fronts and stock usdm S14 rears). This is also the correction split point for S13's. As luck should have it, the Z31 mc's bolt onto our brake boosters, only need to bend the stock hardlines to the new port positions on the MC. In addition (I believe), for us non-abs S14's all Z31 Non-Turbos were also ABS free, so you don't need to modify open up the extra port and chop up your stock MC (like you need to do for Z32 MC's). I will verify this last part in a few days, when my z31 MC shows up. So this should be a great way to get Z32 front brakes without sacrificing brake bias. Also, if you still wanted more rear bias, you could upgrade to Z32 rears which I'm sure would give you more than enough.

Cheers.

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